Telephone-exchange system



A. E. LUNDELL TELEPHONE EXCHANGE SYSTEM Aug. i4, i9.

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A. E. LUNDELL A TELEPHONE EXCHANGE SYSTEM Filed Sept. 21 1918 3 Shams-'Sheet 5 Y Patented ug. 1 4, 1923.

U-.Niien s'ifa'rss Lt-,ils ASFATEN'i @FFME ALBEN E. LUNDELL,.OF NEW YORK, N."Y., ASSIGNOR TO "WESTERN ELECTRIC OQMPANY, INCORPORATED, Or- NEW YORK.

VApplication filed. September 21, 1918.

To all whom t may concern: s

Beit kno-wn that4 I, ALBEN E. LUNDELL, a citizen ofthev United States, residing at New p York, in the county ofBronX, State of New v5 York, have invented certain 'new and useful Improvements in Telephone-'Exchange Systenis, of which the following is a full, clear, concise, and eXactI description.

This invention relates to telephone exchange systems, and particularly to an iinproved arrangement for controlling the operation of selectively Operable switching devices employed in machine switching telephone exchange systems.

' It is `the object of the present invention to provide an` arrangement whereby, in response to the adjustment of a controlling apparatus, the setting of a selectively operable switching device may be effaced, preferably I by restoring the switching'device to normal.

Nith this object in View, according to one feature of the present invention the restoring nie-ans,VV such as the restoring magnet or adevice controlling the opera-tion of the re- 2:5 storing magnet, of a selectivelyl operable switching device may be actuated under the control of the apparatus, the adjustment of which determines the operation of the switching device. Due to the provision of this arrangemennpan operator or subscriber controlling by means Of an apparatus, suchl as a substation or centralotiice sending device, the setting of a selectorswitch, may, by operating`v the sending device, cause the :"restoration of the selector if the sending device has been erroneously operated. i According to another feature of the invention, a selectively operable switching device Hmay be'restored in response to a selection 40 controlling operation of the controlling apparatus, whereby if, e. a semi-automatic operator notices that shel depressed a wrong v key on her sender controlling'keyboard, she

will 'simply have to depress the correct key,

whereupon the selector switch, operated in4 accordance with the 'designation of the wrong key. isrestored and is aga-in'caused to operate butin accordance w'itlithe designationfof the correct key. l

s These and other features of the invention will be more readily understood from the following description off' a preferred embodiment of the invention and the appended I claims.l Y i` YORK, N. Y.,A fi CORPORATION or Y TELEPHONE-EXCHANGE SYSTEM.

sensi No. 255,114.

In the drawings, Fig. 1 represents a semiautomatic telephone Operators cord circuit terminating in selectively operable switch- L ing device; big. 2 (to be placed below Big. l) represents the operators sending and controlling apparatus, and Fig. 3 (to be placed to the right of Fig. 1) represents a second selectively operable switching device.

Only so much of the circuits and apparatiis ofV a semi-automatic telephone exchange is disclosed in the drawings as is necessary for a clear understanding of the present invention. The selector switches are preferably of the saine-type as the one disclosed in Patent No. ,1,123,696 to E. B.

Craft and J. N. Reynolds, and the sequence switches of the structure disclosed in Patent No. 1,127,808 to J. N. Reynolds and C. F. Baldwin.l For the sake of simplicity the selectors are shown as provided with only one set of wipers instead of five sets as disclosedvin the patent, and for this reason the tripping mechanism of the patent has also been left. out. All the sequence switch cams shown in a figure are controlled by the sequence switch illustrated in that ligure. The showing of the sequence switch cams is diagrammatic and not in accordance `with their structural relation to the sequence switch power magnets'. In practice, the operators sending and controlling equipment is not permanently associated with a cord circuit, but is selectively and automatically associated with a cord c'zrcuit taken for use by -means of a cord finder. A complete disclosure of the circuits ofthe Operators sending and controlling apparatus and the selector' switches may be had from Patent No. 1,168,319 to A. E. Lundell. `However, it willobviously appear tO those skilled in the art that this invention 9 the lighting of'a calling lamp 102 signals the operator o f the presenceof a c all at her board; The Operator thereupon inserts the answering plug 103 of one of her cords into the answering` jack 104 in whichthe calling line terminates. A circuit is closed there- The relay 100 closes a circuit from ground,

through its armature and front contact, the upper lett-hand contact of sequence switch cam 10'( and the power magnet 01:l sequence switch 108 to O'rouiidedbatter The se-` quence switch is moved outot positionpl and under the control oi its no 1mal contact109 into position 2. A circuit is now closed from ground, through the lower Contact of sequence switch cani 110, conductor 111, the

upper contact of sequence switch cam 200 and the winding of a relay 201, to grounded battery. Relay 201 becomes energizedA and closes a circuit from ground, through its lett-hand armature and fi'ontrcontact, the

pper right-hand contact of sequence switch Y cam 202, and the power magnet of a se` quence switch 203, to grounded battery. The sequence switch is moved out of position 1 I and under the control of its normal contactV 2011, into position Il. Therelay 201 does not become deenergized when the sequence switch 203 moves out of position 1, because a locking circuit is closed for this relay in positions 1 to 10 of the. sequenceswitch203,

from grounded battery, through the wind-V ing of this relay, the lowei contactot sequence switch cam 200, the right-hand contact and armature of`i'elay201, conductor 205,7and the upper contact of sequence switch camv110, to, ground. Y

In the meantime the operator has conversed with the calling subscriber by connecting her telephone headset 112 by means of listening key 113 or other well-known device to thc connecting circuit taken `for use. Having Vlearned the Vnumber of the desired subscribers line, the operator adjusts lier controlling equipment by depressing actuatingmeinbers, such askeys, representingthe digits of the called number.,V 1n the present case it will be assumed that she depresses keys 2,06 and 207. The operator depresses also her start key 208, which will cause the sending out ot the impulses under the control of keyl 207 after the sending of the impulses under the control of key 206 has terminated. The keys in one row with `key 206 adjust the sending apparatus .to

1 control the operation of selector `122, and

Y cov those in one rowwith-key 207` adjustthe apparatus to control the operation otA selector 300 in accordance with the .digits ot.;

the called number. Y

i V position e ot4 sequenceeswitch 203, a circuit is closed from grounded battery, through the winding;l of ielayf114,,tlielower righthand contact of cam 116, conductor 115, the

outer armature andlback contact-:ot :the upper zero counting relay,VV the winding ot a stepping relay 210, the upper VContact ot cam 209, conductor 211, and the lower contact of sequence switch cam 117, to ground. Y.

of position 2 and into position A circuit is now .Y closed trom grounded battery, through the winding of ainagnet119, the left-hand contact of sequence, switch cam 120, and the right-handfront contact and armature 'ot'relay 114-, to ground. Magnet 119 becomes energized and by attract-ing its armature presses brush rod 121 of the selector 122 against an up-drive roller 123 constantly rotating in the direction indicated by the arrow. `Wipers 124, 125 and 126 andcoininutator A'brushes 127 and 128 ot the selector 122 carried bythe brush rod are moved in anupward direction. The

wipersk 1211 to 126are `arranged to engage Y terminals of a bank 129 in which terminatev called lines such Vas the trunk leading to Ysiii selector 300. The cominu'tator brushes 127 and 128 are arranged to engage the conducting and insulated portions ot commutator segments 130 and 131,V respectively.

Upon the actuation of the key206, a circuit was closed trom ground, through the.

i"iontl contact and lett-handarniature ot relay 201, contact otkey 20,6.resistance 251. and the winding ot relay 250. Relaym250 is marginal in operation and does not becoine energized by current 'flowing in this circuit. In response Vto the energization ot relay/'210. a circuit Yis closed from ground, through the arinatureand liront contact` ot this relay, the Vupper contact ot'sequence switch calm 220, contact 221 otV the key 206, andthe winding oi' the lower counting relay 0, to` grounded battery. This counting relay becomes .energized and'closes a locling circuit for itselt' Jfrom ground, through the right-hand contactA of sequence switch cam 222, the armature andv front,` contact cause ot a shunt pathl closed to itswinding `through the armature and front'contact of, relay 210, to ground. As soon as the coiiifA mutator brush 127 engagesgior the first time the conducting portion ot cominutatorsegnient 130, a shunt path is closed from ofthe wipers otV selector 122.

ground, through commutat'or brush 127, the

the stepping relay 210 is not suicient toV maintain it energized, and this relay, by retracting its armature, permits the energization of the upper counting relay 0. The upper counting relay 0 opens in its outer back contact the above traced circuit of relays 210 and 114. The relay 210 becomes deenergized. The relay 114, however, is maintained energized by current Vflowing through the above traced' pat-hV including conductor 132 and the coinmutator brush 127, as long as this commutator brush `is in engagement with the conducting portion ofthe segment 130.

As soon, however, as this commutator brush engages the insulated portion of the segment 130 (at which time the selector switch wipers are centered on the selected set ot terminals). the relay 114 becomes deenergized and by opening its right-hand front contact the circuit of magnet 119 causes the arresting ot the upward travel A circuit is also closed from ground, through the righthand back contactand armature ot relay 114, the left-handcontact of cam 118, and the power magnet of sequence switch 103, to grounded battery, for driving this lswitch out of posit-ion 3 and into position 6. A circuit is now closed from ground, through the lower and the upper right-hand contacts ot sequence switch cam 135", and the righthand winding ot relay 136, to grounded battery. The relay 136 becomes energized and closes a circuit from ground, through its right-hand armature and front contact, the

Y' right-hand contact of sequence switch cam -137, and the power magnet ot sequence switch 108, to grounded battery, for driving this sequence switch out of position 6 and into position-7., t,at this time, the selector 122 is resting with its wipers onthe terminals of a busy trunk, that is to say, on terminals the multiples of which are engaged by the wipers ot another selector, the test terminal with which the wiper 124 contacts is-connected to ground in a manner to be hereinafter set forth.

VFor this reason upon the energization ofthe relay 136, a` locking circuit is closed from grounded battery, through the left-hand winding, front contact and'left-hand inner armature ot4 relay 136, and the wiper 124'to ground at the other selector. The relay 136 being-'energized, as soon as the sequence switch 108 reaches position 7 a circuit' is closed from ground,` through the right-hand armature and front contact ot relay 136, the righthand contact of cam 120 and the winding ot magnet 119, to grounded battery. The magnet 119 again becomes energized and causes the further travel ot' the vselector switch wipers in an upward direction. The selector switch wipers willcontinue to travel until the test wiper 124 encounters an Vidle test terminal, that is to say, one to which no ground is connected, whereupon the locking circuit of the relay 136 is opened. In the Vpresent cas-e,y it is assumed that such idle trunk is the one designated by the numerals 140, 141 and 142. Upon the deenergization of rela-y 136, the circuit of magnet 119 is opened and a circuit is closed through the right-hand armature and back contact ot relay 136, the left-hand contact of cam 137, and the power magnet of sequence switch 108, to grounded battery, for moving this sequence switch out ot position 7 and into position 11. The multiples of the contacts in which trunk conductors 140, 141 and 142 terminate are guarded against seizure by other selectors due to the connection of a ground through the upper lett-hand contact of cam 117, the left-hand inner back contact and armature of relay 136, and the wiper 124. This ground is alsoy extended through conductor 140 and the winding ot' a relay 301, to grounded battery, causing the energization of this relay.

At the sender, the upper zero counting relay closed a` circuit from ground, through the left-hand contact of' Vcam 222, the inner armature and front cont-act ot the upper zero counting relay and the power magnet or" sequence switch 203, to grounded battery, causing the movement of this sequence switch out ot position 4 and into position 5. F rom this position the sequence switch is moved into position 6', the driving circuit being closed from grounded battery, through the power magnet of the sequence switch, the lower contact of cam 202, and the contact of the key 208. In positions 4 to 8 of the sequence switch 203, a circuit is closed from grounded battery, through a resistance 260, sequence s vitch cam 261 and the lower winding of relay 230 to ground. Current iowing through Vthis circuit polarizes the relay 230 in such a manner that the relay will not attract its armature unlessr its upper windingis traversed by current flowing in a. certain direction.

As soon as the sequence switch 10S reaches position 11, a circuit is closed from ground, through the letthand contact or sequence switch cam 304, conductor 141, wiper 125, the upper contact of sequence switch cam 144, conductor 211, the lower contact of sequence switch cam 209, the upper winding of a relay 230 and a non-inductive resistance 262 in parallel, the winding ot relay 210, the outer back contact and arma-ture oit the upper counting relay 0, conductor 115, the lower contact of cam 143, wiper 126, conductor 142,

the Alower right-hand contact of sequence switch cam 303, and the winding ot' relay 302, to grounded battery. Relays 210 and 309J become energized. Relay 230, however, does not respond to currentr tlowinj in this direction through its `upper winding. The non-inductive resistance 262 is provided. so as to insure the proper operation of relay 210. Relay 302 closes a locking circuit for itself through its left-hand armaturefand 'l'ront Contact,l and lower left-hand contact of sequence switch cam 303, and a circuitrlirom ground, through its right-hand armature and .front contact, thelower lett-hand contact of sequence switch cani 305, and the power mag.- net ot sequence switch 306 to grounded battery. rlhe sequence switch is moved out of position 1 and under the control of its normal contact 307 is-moved to- Josition 2. InV

this position of the sequence switch, a circuit is closed from ground, through the righthandarmature and front contact of relay 302, the lower contact ot sequence switch cam 303, and the winding of a magnet 309, to

Y lrounded battery. Magnet 309 by attracting its armature, presses brush rod 310 of the selector 300 against a roller 311'constantly rotating in the direction indicated by the arrow.v The wipers 312, 313 and 311 and .the con'imutator brushes 315 316 and 31'?- carried by the rod 310 are elevated. The wipers 312 to 314` are arranged to make contact with the terminals ot a bank 318 in'which called lines, such as trunks leading to another selectively operable switching device, terminate, and the brushes 315 to 317 are arranged to engage the conducting and insulated portionsot commutator.segments 319, 320 and 321, respectively. e

Upon the energization of the relay 210, a circuit is closed from ground, through the front contact and armature of this relay, the lower contact of cain 220, the contact of key 207, the armature and back contact of the upper counting relay 1, thev winding of the lower Vcounting relay 1, to grounded battery.Y

'llhel'ower counting relay becomes energized and closes a locking circuit for itself Vfrom ground, through the right-hand contact of sequence switch cam 222, the armature and iront contacter the lower counting relay 1, andthe windings 'of the upper and lower counting relays 1, to grounded battery. .The upper counting relay 1 does not become energized, because of the shunt path closed to its winding from ground, through the front contact ot the stepping relayf210. However, as soon as the commutator 'brush 316 engages Vtheconducting portion 4of commutator segment 320, and connects ground'through the lett-hand contact of sequence switch'cam 303 to the winding of relay 302, the stepping relay 210 is shunted out. and by retracting itsV armature, permits: the energization of the upperc'cunting relay 1, whichVV in turnY extends` the counting relay circuit to the lowercounting relay 0. `When the commutator vbrush 316 engagesthe insulated portion of segment 320, the stepping relay 210 becomes again en ergized and causes in turn the completion of the circuit for the-lower counting relay 0.

ll'lhen the commutator brush again engages the conductingportion ofV segment 320, the

upper counting relayrO becomes energized from ground, through cam 263, conductor Y 2641, lower contact of cani 107 and the power magnet of switch 108 to grounded battery, for moving this switch out of position 11 and into position 16.V Lamp 152 is lighted. It is again noted `that in practice a larger number of selective operations arey performed than are disclosed in the present embodiment of the invention. Y

1Nhile these selective operations occur bef yond the selector 300, the sequence switch to position being controlled by the upper.

zero counting relay in the abovev described manner. Vhen the last switchl in the series (the connector switch) is set, the sequence switch 203 is moved into position 16 and causes in turn the movement of sequence switch 108 out of ,position 11 and into position 16. Y l e VWhenthe sequence switch 108 moves out of' position 11, it opens in the upper contact or' cam 110 the locking circuit of relay V201.

This relay becomes deenergized and closes a) circuit through the left-hand contactotcam 202, Jfor moving sequence switch A203 out of position 16 into position 1. The sender is now restored to normal and ready or'use Vin the control of the establishment of another connection. VThe keys are restored to normal in ythe same manner` asillustrated in the mentioned,Patent No. 1,168,319. Y

The opening of the back Contact of the upper counting opening of the circuit including relays 210 and 302. VRelay 210 ,becomesV deenergized. Relay 302, however, is maintained'energized through the path including the commutator brush 316 as long as this brush rests on vthe conducting portion of segment'302. As soon, however, as this brush engages the insulated portion of commutator 320, which indicates relay 0 also results in the,

that the wipers are properly centered on the proper set of terminals, the relay 302 becomes deenergized, and by opening the cirf cuit of magnet 309, causes the arresting of the selector 300. The relay 302 also closes a circuit from ground, through its right-hand armature and back contact, upper lett-'hand contact of sequence switch cam 305, and the power magnet of sequence switch 306, to grounded battery, for moving the sequence switch out of position 2 and into position 5. A circuit is then closed from ground, through the sequence switch cam 322, the left-hand winding ot' a test relay 323, to

grounded battery. This relay becomes energized and closes a circuit from ground. through its left-hand armature and front contact, the lower right-hand contact et' sequence switch cam 324,.and the power magnet of sequence switch 306, to grounded battery, for moving this sequence switch out of position 5 and into position 6. Uponenergization, the relay 323 prepa-res a locking circuit for itself from grounded battery, through its right-hand winding, front contact and armature and the test wiper 312 ot the selector 300'. It the terminals on which the selector wipers are lnow resting are busy, then the test wiper 312 nds ground. For this reason, the relay 323 is maintainedenergized and closes a circuit from ground, through its left-hand armature and front contact, the upper contact of sequence switch cam 308, and the winding of magnet 309 to grounded battery. Under the control ot' magnet 309, the selector' is caused to further travel in an upward direction until the testv wiper 312 encounters the terminals of an idle truiik, that is to say, a terminal to which no ground is connected. Relay 323 becomes deenergized and connects ground through the contact of sequence switch cam 325, the right-hand back contact and armature of relay 323, and the test wiper 312 to the multiples of the test terminal engaged by the selector, whereby lthe terminals of this trunk will test busy at all selectors attempting to make connection therewith. The `deenergization of relay 323 results also in the closure of a circuit from ground through the left-hand armature and back contact ot relay 323, the upper right-hand contact of sequence switch cam 324 and `the power magnet of sequence switch 306 to grounded battery, 'for moving this sequence switch out of position 6 and into position 16.

In practice the sequence switch 306 is not moved immediately from position 6 into position 16, but is stopped in intermediate positions Vior cooperating in the control of selectively operable switching devices .employed in the extension of the desired connec-tion beyond the selector300. However, it is thought that the present invention will be clearly understood without descqribing in detail these operations, and for this reason it is assumed that the connection is :turther extended to the called subscribers station and that the called subscriber has been signaled and removed his receiver from the switchhook in answering the call. The circuit of a supervisory relay 326 is then -closed in the well-known .manner through the called substation, and this relay in turn closes the circuit of a relay 327. In position 14 of the sequence switch 306, a circuit was closed from grounded battery, through the left-hand winding ol a relay 328, the outer back contact ot" relay 32T, the lower right-hand contact of sequence switch cam 304, conductor 141, wiper 25, the lower contact of sequence switch cam 114, the secondary winding of a repeating coil 150, the winding of a polarized relay 151, the secondary winding of repeating coil 150, the upper contact ol sequence switch cam 143, wiper 126, conductor 142, the upper righthand contact yof sequence switch cam 303, .the primary winding of repeating coil 329, the inner back contact of relay 327, and the right-hand winding of relay 328, to ground. The relay 328 became energized and caused in turn the energization or a slow-acting relay 330. The polarized relay 151, however, did not become energized by current liowing through its winding in this direction. Upon the energization of the relay 327, the direction of the current liowing through the abovetraced circuit is reversed, whereupon the polarized relay 151 becomes energized and causes the extinguishment ot lamp 152, indicating to the operator that the connection has been completed.

then ndisconnection is desired the calling and called subscribers restore their receivers to the switchhooks, whereupon the supervisory relays 326 and 153 become deenergized. The relay 326 causes the deenergi- Zation of relay 32T which reestablishes the circ-uit including relays 328 and 151 to its original condition, whereby the polarized relay 151 becomes deenergizefl. Both lamps 152 and .154 are lighted now at the operators position, indicating that disconnection is desired. The operator then removes plug 103 from jack 104, whereupon relay 106 becomes deenergized and closes a circuit r'rom ground, through its armature and back contact, the right-hand contact of sequence switch cam 107, and the power magnet of sequence switch 10S, to grounded battery, for moving this sequence switch out oit' position 16 and into position 18. A circuit is now closed from ground, through the right-hand contact of sequence switch cam 117, and the winding of a restoring magnet 155 to grounded battery. Magnet 155 becomes energized, an d4 by attracting its armature, presses the brush rod 121 against a roller 156, constantly rotating in the direction indicated by the arrow. Under the control oli this roller the brush rodL 121 is caused to travel in a downward direction. Then the brush rod is restored to its normal position, the commutator brush 128 is f inengagement with the conducting-segment V18 and into position 1, whereupon the magnet 155 becomes deenergized.' When the sequence switch 108 is moved out olf position 16 the ground is disconnected from thev selector wiper 124, whereupon the relay 301 becomes deenergized and closes a circuit from ground, through its back contact and armature, the lower right-hand contact of sequence switch cam 305 and the power magnet of sequence'switch 306, to grounded battery, for moving this sequence switch out of position 16 and into position 17. The movement of the sequence switch 108 out ot position 16 results also in the deenergization of relay 328, which inturn causes the deenergization of relay 330.V Upon the deenergization ot' relay 330 a circuit-is closed from ground, through thel armature 'and back contact of this relay, the lower lefthandcontact of sequence switch cam 324C and the power magnet of sequence switch V306, to grounded battery, for moving this sequence switch out of position 17 and into position 18. A. circuit is then closed from grounded battery, through the winding of a restoring magnet 330, and a sequenceswitch cam 331, to ground. The magnet 330 becomes energized, and by attracting its armature, presses the rod 310 against a roller 332, constantly rotating in the direction indicated by the arrow. Under the control of this roller, the brush rod is caused to travel in a downward direction, and when it is restored to its normal position, the commutator brush 317 engages a conducting segment 333, connectingground through the upper left-hand contact of sequence switch cam 324 Yto the power magnet of sequence switch 306, for moving this sequence switch out of position 18 and into position 1. The magnet 330, is then deenergized. The switches are now restored to their normal position, and may be employedin the establishment of a new connection.

As above stated, due to the marginal adjustment of the relay 250, the closure ol a circuit including its winding and a single resistance251 does not result in the energi- Zation of this relay. Assuming that the operator instead ot' depressing key 206, depressed by mistake key 252 when desiring to establish the above described connection. The actuation ofthe key 252 results immediately inthe adjustment of the sender for controlling a certain operation, diti'erent V'to lthe actuation of key 252, the counting relays are adjusted to receive two impulses from the selector 122, causing the selector to engage the terminals of a different group of trunks from that engaged infresponse to the actuation of the'key 206. The operator then proceeds to actuate the otherV keys on her keyboard, but lbefore depressing her start key 208, notices that she depressed the wrong key in the lirst row on her keyboard. 1n orderto correct h'er error all she will have to do is to depress the proper key, that is tosay, key 206. -Each row ot keys is provided with a mechanicalinterlocking device, whereby the depressure of a key causes the restoration of a key held in itsactuate'd position. 252 and '206 are maintained' simultaneously actuated, and lor this reason two resistances 251 and 251eA are'connected in parallel to the windingv of 'marginal relay 250. The marginal relayV 250 becomes momentarily energized and closes a circuit from ground, through its front Contact and armature.l conductor 253, the lower contact of sequence switch cam 160, and the winding of a relay 161, to grounded battery. The relay 161 closes a locking circuit Jfor itself from ground, through its right-hand armature andv front contact, the upper contact'ot sequence switch cam 160, and the winding ot' relay 161. to grounded battery. The sequence switch 108 ot therselector 122 is now in some position between 2 and 7. The relay 161closes a circuit from ground, `through its let-hand'contact' and armature, the lower contacts of sequence switchA cam 162, and the power magnet of sequence switch'108. to grounded battery.A Under the control oi' this circuit the sequence switch 108 is moved out of whatever position `it may be in and into position 8. The magnet 119 Vof the selector is deenergized and the magnet 155 energized by current flowing through a circuit extending from grounded battery, through the winding of magnet 155, the upper righthand and lower left-hand contact of sequence switclrcam 162, and the left-hand armature and front Contact of relay 161, to ground. Under the control of the magnet 155, the selector 1.22 is restored to normal in the above described 'mannen and when it reaches its normal position, the brush 128 closes a circuit, through the yconducting portion of segment 157,101' moving the sequence switch 108 out of position 8 and into position 1. The magnet 155 and the relay 161 become (leenergized. As soon as the sequence switch 108 reaches position 1, it is driven into position 2 by the circuit closed through the VVfront Contact of relay 106, and then the setting o1 F or a. short time, however. keysV lthe selector 122 under the control of key 206, yis accomplished in the above described manner. A

It will be seen from the above that, due to the provision oi the means including the -resistances 251 and the relays 250 and 161., the operator may correct an error she made in selecting a key in one row, Without the necessity of disturbing the properly selected keys in the other rows. The invention may be applied to other rows of keys than the -irst row, to a plurality of rows of keys representing various digits., or to substation senders for full-auuton'iatic telephone exchange systems. The invention is disclosed in its present form, because it has been observed that semi-automatic operators make a relatively large `number of mistakes in `se:- llecting the proper key in the irst row which designates `the'district or oilice in which the called line terminates.

If all the trunks belonging to the group selected by selector 300 are busy, then the Aestablished portion of `the connection is released. This is accomplished in the ollow ing manner:

The commutator segment 319 is so arranged with respect to the segments 320 and 321, that if all the trunk lines ina selected group are busy, then after the last trunk line in the group. has been tested, the commutator brush 315 is in engagement with the conducting portion of segment 319. rThe sequence switch 306 being in position 6 during the hunting operation of selector 300, a circuit is closed from ground, through commutator brush 315, the c-onducting portion of segment 319, the upper-right hand contact of cam 305, and the power magnet ot' sequence switch 306 to grounded battery, whereupon this sequence switch is moved out of `position 6 into position 17. The driving magnet 309 becomes deenergized.

After the termination of the group selecting operation, the sequence switch 203 moved into position 8. Therefore, when the sequence switch 306 .reaches position 17, the relay 230 becomes energized, its upper winding being traversed by current flowing from grounded battery, through the outer back contact of relay 327, the primary winding of repeating coil 329, the right-hand contact of cam 304, conductor 141, wiper 125, the upper Contact of cam 144, conductor 211, the upper contact of cam 209, the upper winding 4of vrelay 230, the windings of stepping relay 210, the outer armature :and back contactof `the upper zero counting relay, conductor 115, the lower contact of cam 143, wiper 126, conductor 142, the upper right-hand contact or cam 303, the primary winding of repeating coil 329, the inner back contact of relay 327, and the right-hand winding of relay 325 to ground. The relay 230 closes a circuit through its front Contact and armature formoving the sequence switch 108 out of position 11 and into position 16, whereupon the locking circuit of relay 201 is interrupted and the sequence switch 203 is moved into posi-l tion 1.

In positi'on 17 of sequence switch 306 an inte1'r11ptei'340 is connected through the con tact of sequence switch cam 341 to the relay 326, and causes this relay to intermittently energize and deencrgize. Through the .agency yof relays 327 andill the relay 326 causes the flashing of lamp 152, which indicates to the operator that all the trunks are busy. She may then restore the connection in the above described manner.

Wvhat is claimed is:

1. In a telephone exchange system, a calling and a called line, means including a selectively operable switching device for interconnecting said lines, a variably adjustable controlling apparatus, means to adjust said apparatus to a setting' in accordance with the designation of said called line, means dependent on the adjustment of said apparatus Jfor variably operating said device, means to readjust a portion orn the setting of said apparatus, and means operative thereupon to operate said device in accordance with said readj usted setting.

2. In a telephone exchange system, a. calling and a called line, means including a selectively operable switching device for interconnecting said lines, a variably adjustable controlling apparatus, means responsive to each adjustment of said apparatus for variably operating said device, and restoring means for said device operated in response to any one of a plurality of adjust-ments of said apparatus. t

3. In a telephone exchange system, a calling and a called line, a switching device, a variably adjustable controlling apparatus, means dependent on the adjustment of said apparatus for causing` said device to interconnect said lines, means to readjust said controlling apparat-us, restoring means for said device operable at will, and means incidental to the readjustment of said apparatus for operating said restoring means.

4. In a telephone exchange system, a calling and a called line, a switching device, means including a controlling apparatus for causing said device to perform a plurality ot' operations, a connecting circuit between said lines established upon the completion 'of all ot said ope-rations, restoring means for said device controlled by said apparatus, and means for rendering said last mentioned control effective 'only during certain operations ot said device.

5. In a telephone exchange system, a calling` and a called line, two selectively operable switching devices, a variably adjustable controlling` apparatus, means responsive to the adjustment et saidapparatus tor succes- `sively controlling said devices to interconnect said lines, a restoring means tor one of said devices controlled by said apparatus, and means for rendering said last mentioned control eiliective only prior to the operation of the other one ot said devices.

device, restoring means for said device, means ior adjusting said apparatus in accordance with the digits oi' the called number, means for changing the adjustment oi' said apparatus with respect to one or' the digits, andV means operative thereupon for actuating said restoring means.

7. In a telephone exchange system, acall-k ing and aL called line, a selectively operable vswitching device arranged to interconnect said lines, a sender for Vcontrolling said device, 'restoring means for said device, means including a plurality of actuating` members Yfor variably adjustingsaid sender, means responsive to the operation ci' any one of Vsaid actuating' members for controlling said switching device in accordance with the adjustment of said sender, and means responsive to the operation olI more than one actuatingmember ior operating said restoring means. Y 8. In a telephone exchange system, a calling and a called line, aV sel-ectively operable switching device arranged to interconnect said lines, a sender lfor controlling said device, restoring means for said device, means including a plurality of actuatingmembers for variably adjusting said sender, means responsive to the operationof any one ot said actuating members ior controlling' said switching device in accordance with the adjustment of said sender, and means responsive to the simultaneous operation ot' a plurality oil members for operating said restoring means. Y Y

' 9. In a telephone exchange' system, a call,- ing and a called line, means including a selectively operable switching deviceI 'forinterconnecting` said lines, a variably adjustable controlling' apparatus, means operative in response to a certain adjustment of said apparatus for causing` said device'to pei'- orm a certain operation, restoring means for said device operable in response to certain other adjustment of said apparatus, and means operative upon restoration ot said device for causing it to perform arcertain other operation in accordance with said c ertain other adjustment oi said apparatus.

10. In a telephone Xchange system, a calling and a called line, means including aA selectively operable switching device for interconnecting said lines, a vai'iablv adjustable controllingapparatus 'tor said device, restoring means for said device, a relay for controlling-said restoring means, and a circuit i`or said relay controlled by said apparatas. Y

1l.y In a telephone exchange system, a calling and a called line, means including a selectively operableV switching device for. interconnecting' said lines, a variably operable controlling apparatus comprisinga plurality of switches, means responsive 'to the vactuation of each switch torc'ontrolling the operation of said device, restoring means for said device, a marginal relay VAfor controlling said restoring means, acircuit for said relay having a resistance in each of said branches, and means controlled by each of said switches for closing a branch. y

V12. In .a telephone exchange system, a calling and a calledline, means including a selectively operable switching deviceY for interconnecting said lines, an operators controlling apparatus comprising a plurality of keys, means responsive tothe actuation ot each key for selectively controlling the op- Y eration of said device, restoring means for said device, and means responsive to the actuation ot a key for operating-'said restoring means. Y Y j 13. In a telephone Vexchange system, a callingl and a called line, meansincluding a selectively operable switching device forin- -terconnecting said lines, an operators controlling apparatus comprising a plurality of keys, means responsive to the actuation of each key for selectively controlling the operation of said device, restoring means for said device, and means responsive to the simultaneous actuation of a Vplurality of keys for operating said restoring means.

V1li. In a telephone exchange system, a callingand afcalled line, means including a selectively operable switching device for interconnecting saidlinesgan operators controlling appaiatus-comprising a plu-ralityof keys, means responsive to the actuation of each key for variably controlling the Aoperation of said device, restoring means forsai'd device, a relay for controlling saidrestoring means, and means controlled bysaid keys forop'erating said relay Y 15. In a telephone Vexchange system, a calling and avealled line, two switching devices, a controlling apparatus, Vmeans'con- "trolled by said apparatus for successively Voperating said'devices Vto interconnect said lines, means for rendering busy said called line, a restoring means for each of' said devices, means for actuating the restoring means ofeach device if the 'called' line is busy, and means controlledby said apparatus for controllingtthe restoring means of oneot said devices. V Y' 'In witness whereof, I hereunto subscribe my name this 31st' day of August, A. D., 1918.

ALBEN E. LUNDELL.

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